The development of rat molars was investigated histologically from immediately after birth to the 35th days. Furthermore, a histochemical and scanning electron microscopic study was carried out concerning mainly the development of the tips of the cusps lacking of enamel, "enamel free area". The following results were obtained. 1. The sequence of development and eruption of rat molars was as follows : M_1, M_2, and M_3. There was little difference between upper molars and lower molars. The first molar in the lower jaw and the third molar in the upper jaw erupted slightly earlier. The second molar erupted in both upper and lower jaws at approximately the same time. 2. The cells at the center of the cusps where enamel free area occurred, morphologically showed similarity with the inner enamel epithelium cells in early stage. The cells at the inclined plane of the cusp differentiated into the long columnar ameloblasts, while the cells at the center of the cusp changed into the small cells. These small cells existed on the surface of dentin of enamel free area until eruption. The cells of stellate reticulum and outer enamel epithelium cells, which had transformated stratified squamous epithelium immediately before eruption, were observed on the dentin surface, connecting each other. 3. The stratum intermedium at the enamel free area showed slight development before the formation of predentin and these cells gradually dispersed and finally disappeared. 4. The histochemical study were made of phosphatase, dehydrogenase, glycogen and mucopolysaccharide before and after the development of cnamcl free area. Consequcntly, in the case of ALP, ACP, SDH, LDH, NADH and NADPH, the activity of inner enamel epithelium cells and stratum intermedium cells at the enamel free area showed difference in comparison with those of enamel forming inclined plane of the cusp. It was elucidated that the deficiency of these enzymes correlated well with the development of enamel free area. 5. The findings of enamel free area by the scanning electron microscope indicated a layer of adhesive material covering the surface immediately before eruption and generally reticular structure in the surface of dentin locating below it. However, the picture showed diversity, with moderate calcification or slight calcification.

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The changes of taste buds of the rabbit foliate papillae induced by the administration of Bleomycin (BLM) were observed under optical and electron microscopes. Applicable dosage for human body represents 0.3mg/kg while 5 times as much as used for the first BLM administration. The rabbits used in these experiments were grouped into two groups with one administrated only once while the other was administrated continuously in the range of 5 through 10 times in 24 hours intervals. Examinations on taste buds for the total of 35 rabbits were undertaken after 60 minutes, 24 hours, 7th day, 10th day, 20th day and 30th day of the BLM administration. The results of the experiments are as follows : Optic microscopical findings : 1. Taste cells were almost identical as normal cells with little changes being observed after 60 minutes of the first BLM administration. However, many taste buds were penetrated by leucocyte as a resulting abnormal phenomenon of the BLM administration. 2. Major changes took place in type II cells after 24 hours of the first BLM administration. The degeneration of cells was found in the forms of vacuolization of cytoplasm and distortion of nucleus, however, the number of transformed cells decreased in course of days. 3. The changes were also observed in type I cells after 24 hours of continuous BLM administration, i.e., atrophy of cytoplasm as well as distortion of nucleus being attended with an increase in the size of intercellular space. 4. In course of time after the BLM administration was conducted, a large number of cell cleavages was witnessed around the edges of taste buds, with most of those cell cleavages moving into taste buds while they were being segmented. Electron microscope findings : 1. The vacuolization and dilation of ER and mitochondria were observed after 60 minutes of the first BLM administration. All the leucocytes penetrated into taste buds were found to be neutrophil leucocytes. 2. The appearance of degeneration of type II cells became more conspicuous while the same kind of phenomenon was taking place in type I cells. A minor degeneration in type III cells was observed with a slight increase in the amount of filament in each cell. The secondary lysosome was found in each of those cells. The cells other than type II cells became normalized after 10th days of the BLM administration. 3. Not only vacuolized-distorted cells but also the atrophy of cytoplasm and increased electron density were appeared in certain type I cells after 24 hours of continuous BLM administration. Only few r-ER and mitochondria were contained in the above-mentioned cells in which no filament and ribosome were observed. Further vacuolization and dilation were apparent in type II cells. The collapse phenomenon of cytoplasm and of nucleus took place in certain type II cells. The vacuolization of ER and mitochondoria not only appeared in type III but changes in the number of dark cored vesicle and electron density were also observed. Some changes were also found in a part of synapse. Althoush these degenerated cells became normalized with lapse of days, it was noticed that a difference exists with respect to quickness of recovery among type I, II and III cells. By order of quickness or recovery, type I recovered first with III second. However, type II possessed degenerated cells after 30 days of BLM administration. 4. Nuclear body was observed most in type II cells of which forms were classified into three types, i.e., fibrous like, round and beaded like shapes. The beaded nuclear body, especially, was discharged into cytoplasm through enlarged nuclear pores. 5. Binuclear cells were sometimes observed in type II cells. 6. There were certain type I cells of which apical cytoplasms did not form microvilli but reached to the hem of taste pores as a club like projection. To synthesize the above findings, a structual formation of type II cells was found to be most strongly

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A cytoplasmic NADP-dependent isocitrate dehydrogenase was purified to homogeneity from extracts of bovine parotid gland with an overall yield of approximately 30%. The specific activity attained was 45.2 u/mg protein. The molecular weight of the enzyme was determined to be 74, 000±2, 000 by gel filtration and sucrose gradient centrifugation. The enzyme showed a pH optimum of around 8.0 and a requirement for divalent cation, Mn^<++> being the most effective. Mn^<++> also turned out to be a very efficient stabilizer for this enzyme. Apparent Km's were 8×10^<-5>M and 2×10^<-5>M for isocitrate and NADP, respectively. NADPH and palmityl・CoA were found to be inhibitors for this enzyme, whereas α-ketoglutarate, oxalosuccinate, ATP, ADP, AMP, NAD and NADH exhibited only slight or no inhibitory capacities. The inhibition by NADPH was competitive against NADP and noncompetitive against isocitrate. Palmityl・CoA, on the other hand, seemed to be an allosteric inhibitor, since the substrate saturation curve assumed a typical sigmoidal shape in its presence. This last finding, along with the inhibition by NADPH, strongly suggests that the physiological role of this enzyme is to supply NADPH necessary for fatty acid biosynthesis.

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The isolation strains 1092 of the Neisseria were separated from 10 children and 10 adults at the very early of the dental plaque. Biological, biochemical and serological experiments were undertaken on 400 colonies of the Neisseria. In addition, the tests on the glass tube wall adhesive and teeth adhesive were done to the Neisseria sicca and Neisseria mucosa. The following results were obtained. 1. The 1092 isolation strains were gram-negative, catalase-positive and oxidaseactivities Neisseria. 2. The isolation strains of the Neisseria indicated the 618 in children, the 418 in adults, respectively. Thus, the children had 1.3 times as much isolation strains of the adults. 3. The results of the pigment product test for the 400 strains examined were the 170 of the positive (42.5%) and the 230 of the negative (57.5%). 4. According to the saccharide resolution test, the 400 strains of the pigment product test showed the 150 of N. mucosa (37.5%), the 122 of N.sicca (30.5%), the 64 of N.subflave (16%), the 27 of N.flavescens (6.7%) and the 37 (9.3%), which did not belong to the others. 5. The serological results coincided with those of the saccharide resolution strains. 6. The serological classification of the 37 strains which did not belong to the others was the 16 N.sicca, the 13 N.mucosa and the 8 N.subflave, respectively. 7. Both of N. sicca and N. mucosa had the same characteristic of colony form adhesive to glucose, maltose and lactose. They also indicated iodostarch reaction. 8. The Neisseria showed more strong adhesivity to fluctose and glucose than sucrose, and indicated iodostarch reaction. 9. Thus, the evidence was gathered to prove that the Neisseria in the oral cavity took a significant and indispensable part of the very early stage in the dental plaque forming.

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Recently, we had an opportunity to encounter a 3-month female baby suffering from cleft lip, palate and premaxilla, ocular hypertelorism, flatness of nasal bridge and syndactylia. In our country, there have been rarely reported dealing with this syndrome which is congenital disorder with oral manifestation. So, we add this case to the previous reports.

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